1. Field of the Invention
The present invention relates to a method of manufacturing a heat exchanger tube in which a tube for a heat exchanger formed by brazing is manufactured using a sheet material, and a heat exchanger in which a tube obtained by the manufacturing method is incorporated and integrated by brazing.
2. Description of Related Art
An extruded flat multi-channel tube has been used as a tube for automotive aluminum heat exchangers. In order to reduce the weight of heat exchangers, tubes obtained by forming a sheet material have been proposed. Examples of such tubes include tubes 1a and 1e shown in FIGS. 1 and 5 formed by bending an aluminum sheet material into a tube shape so that the end portions are oppositely positioned, tubes 1b, 1c, and 1f shown in FIGS. 2, 3, and 6 in which the end portions are disposed in parallel, a tube 1d shown in FIG. 4 in which the end portion and a portion other than the end portion are disposed in parallel, and the like.
Another example is an inner fin tube 1g shown in FIG. 7 formed by bending a sheet material (in particular aluminum sheet material) into a tube shape so that the end portions are disposed in parallel, inserting a corrugated fin 2 (in particular aluminum fin) into the tube shape so that the end portion of the fin 2 is placed between the end portions of the sheet material, and closing (hemming) the end portions to form an end portion G as a temporarily secured portion 3 (see JP-A-2003-336989, for example).
A heat exchanger is manufactured by stacking the tube 1a, 1b, 1c, 1d, 1e, or 1f or the inner fin tube 1g and a corrugated fin, assembling a header (not shown), and integrating the components by brazing. When using the tube 1a, 1b, 1c, 1d, 1e, or 1f, a filler metal enters the tube through the opening formed in the opposing portion or the parallel portion or the opening facing toward the outside of the tube. When using the inner fin tube 1g, a filler metal enters the tube through the gap in the temporarily secured portion 3 formed by closing the tube. As a result, the amount of filler metal becomes insufficient for the necessary portion, whereby insufficient brazing occurs. In particular, measures to solve this problem have been demanded when brazing an aluminum heat exchanger.
Specifically, a filler metal enters the tube 1a through an opening 11 in the opposing portion and an opening 13 facing toward the outside (portion A). A filler metal enters the tube 1b through an opening 12 in the parallel portion (portion B). A filler metal enters the tube 1c through an opening 12 in the parallel portion (portion C). A filler metal enters the tube 1d through an opening 12 in the parallel portion of the end portion and a portion other than the end portion and an opening 13 facing toward the outside (portion D). A filler metal enters the tube 1e through an opening 11 in the opposing portion (portion E). A filler metal enters the tube 1f through an opening 12 in the parallel portion (portion F).